1. The Field of the Invention
The present invention relates generally to optoelectronic communication devices. More specifically, the present invention relates to a transceiver module in which the diagnostic data and control functions of the remote transceiver to which it is connected are locally accessible without interrupting the transmission of high-speed data.
2. The Relevant Technology
Computing and networking technology have transformed our world. As the amount of information communicated over networks has increased, high-speed transmission has become ever more critical. Many high-speed data transmission networks rely on optical transceivers and similar devices for facilitating transmission and reception of digital data embodied in the form of optical signals over optical fibers. Optical networks are thus found in a wide variety of high-speed applications ranging from as modest as a small Local Area Network (LAN) to as grandiose as the backbone of the Internet.
Commonly, digital communication is accomplished using a model known as the Open Systems Interconnection (OSI) model. The OSI model defines a framework for accomplishing digital communications with seven layers on clients communicating in a network. These seven layers are understood by those of skill in the art, and include from the highest level to the lowest level: the application layer, the presentation layer, the session layer, the transport layer, the network layer, the data link layer, and the physical layer. At the application layer, data is used in end user processes. Data is packaged by each of the other layers of the OSI model prior to being sent using the physical layer. The physical layer defines how the data is actually sent on the network, such as by electrical signals, light carried on optical fibers, radio signals etc. Thus, at the physical layer, actual voltages, light levels and radio amplitudes or frequencies are defined as having certain logical values.
At the physical layer, one method of communicating digital data involves the use of transceivers. Typically, data transmission is implemented by way of an optical transmitter (also referred to as an electro-optic transducer), such as a laser or Light Emitting Diode (LED). The electro-optic transducer emits light when current is passed there through, the intensity of the emitted light being a function of the current magnitude through the transducer. Data reception is generally implemented by way of an optical receiver (also referred to as an optoelectronic transducer), an example of which is a photodiode. The optoelectronic transducer receives light and generates a current, the magnitude of the generated current being a function of the intensity of the received light.
Various other components are also employed by the optical transceiver to aid in the control of the optical transmit and receive components, as well as the processing of various data and other signals. For example, such optical transceivers typically include an electro-optic transducer driver (e.g., referred to as a “laser driver” when used to drive a laser signal) configured to control the operation of the optical transmitter in response to various control inputs. The optical transceiver also generally includes an amplifier (e.g., often referred to as a “post-amplifier”) configured to perform various operations with respect to certain parameters of a data signal received by the optical receiver. A controller circuit (hereinafter referred to the “controller”), which is the focus here, controls the operation of the laser driver and post amplifier.
In addition to controlling the operation of the laser driver and the post amplifier, the controller may collect and manage diagnostic data. Performance characteristics of an optical transmitter and receiver may vary in response to changes in operational conditions like temperature and voltage. For example, the threshold current and slope efficiency of a laser diode vary with temperature. To ensure the quality and integrity of data transmission, various measurement and compensation circuits may be employed by a transceiver to compensate for these changes. The transceiver controller may evaluate operating conditions, such as, but not limited to, temperature, voltage, and low frequency changes (such as receive power) from the post-amplifier and/or from the laser driver, and then adjust component settings to compensate for any changes. The operating condition parameter values, referred to collectively as “diagnostic data”, may also be evaluated by the host computer system which typically has access to the controller via a serial interface.
In addition to, and sometimes in conjunction with managing diagnostic data, a controller may also drive several other transceiver functions, including, but not limited to, the following: (i) setup functions which generally relate to the required adjustments made on a part-to-part basis in the factory to allow for variations in component characteristics such as laser diode threshold current; (ii) identification information identifying the transceiver type, capability, serial number, and compatibility with various standards; (iii) eye safety and general fault detection which are used to identify abnormal and potentially unsafe operating parameters and to report these to the user and/or perform laser shutdown, as appropriate; (iv) temperature compensation functions which compensate for known temperature variations in key laser characteristics such as slope efficiency; and (v) monitoring functions that report various parameter values related to the transceiver operating characteristics and environment such as laser bias current, laser output power, received power level, supply voltage and temperature.
Each transceiver is generally passive with respect to other transceivers. This means that a transceiver simply sends and receives digital data that has been converted to a physical layer level signal without extracting or processing the information represented by the digital data. In other words, transceivers do not generally communicate data to one another for the benefit of the transceivers. Instead, the transceivers communicate data to one another for the benefit of the hosts to which the transceivers are connected.
A transceiver may communicate data for the benefit of the transceiver to the connected host device. For example, a transceiver may be configured to generate digital diagnostic information by monitoring the health of the transceiver. The transceiver may then communicate information about the health of the transceiver to its connected host. This communication typically takes place on an I2C or MDIO bus for communicating between integrated circuits. As a transceiver deteriorates due to age, component failure or other reasons, the host may be aware of the deterioration using such communications received from the transceiver.
Data generated by the controller and the digital diagnostics data described above is generally only available to the host on which a transceiver is installed. Thus, when troubleshooting problems with individual transceivers, a user needs to access the host on which the transceiver is installed to discover any digital diagnostic data about a transceiver. This may cause various difficulties when the host and transceiver are located in a remote location such as on the ocean floor or in remote desert locations.
Some protocols exist where digital diagnostic data can be sent as part of the high-speed data sent on an optical link. However, this generally involves sending the data in some specially defined packet or portion of a packet. Thus to retrieve the digital diagnostic data, the high-speed data is disassembled such as by a framer, the digital diagnostic data extracted, and the high-speed data reassembled. Additionally, if digital diagnostic data is to be added by a transceiver in a chain of transceivers, the high-speed data is disassembled and the digital diagnostic data added in the appropriate portion of the high-speed data, and the high-speed data, including the digital diagnostic data, reassembled. To disassemble and reassemble a high-speed data signal represents a significant unwanted cost in terms of data processing. Additionally, there are time delays as the data is disassembled and reassembled prior to retransmission of the data from link to link.
In other presently existing systems, remote controller and digital diagnostic data may be sent in a high-speed data signal that includes out-of-band data. However, the remote module controller and digital diagnostic data is not accessible unless the local host is configured to receive and display the data in meaningful way. As mentioned above, the host computer system is typically the only available interface between a transceiver module and an end user during operation. Therefore, when a remote transceiver generates and transmits controller or diagnostic data as out-of-band data, end user access to that data depends solely on whether the particular host system in which it operates has the ability to access, process, and then display the data in a meaningful way. And since transceiver diagnostic features are a relatively recently developed technology, legacy host equipment often lack the means to access the data. Newer host equipment, which may be capable of accessing diagnostic data, typically lacks the means to display diagnostic data to an end user. It is therefore difficult for network administrators to determine the status of an individual link and to troubleshoot complex systems.